Some route planning systems exist which utilize fixed road path data stored in a memory to calculate a desired route to a specified destination. In some of these systems, a system user (generally the driver of a vehicle) can specify some road segments which are not to be used or considered in planning a route to a user specified destination. This is done by the user specifying "detour data" wherein such detour data defines the road path data not to be used in planning a desired route. In such prior systems, all the user specified detour data is treated in exactly the same way. Typically all user specified detours are interpreted as applying only to a specific trip to be planned. Therefore, for planning any new trip to a new destination, all desired detour data had to be reentered into the route planning system, even if the user might want to use the same detour data he had specified for a prior trip. Typically the entering of detour data is relatively time consuming. Thus requiring the reentry of detour data into a route planning system is not desired.
Even if a prior system was designed to save all detour information used for one trip such that it would apply to every subsequent trip, many times the detour data entered by the user was just intended to apply to just one trip and/or the entered detour data was just intended to apply to trips to be planned for just a particular identified driver. Thus prior systems did not provide enough system flexibility for handling the entry of user specified detour data such that the detour information was used in a desired manner to accommodate different route planning situations without requiring substantial additional time and effort on the part of the system user/driver.
Some prior route planning systems contemplate the system receiving radio broadcasted detour information. This received broadcasted information is then used for the calculation of all trips by the system for a specified time duration. However, this type of detour information is not detour information which is specified by the user/driver. Also, such a system does not suggest or provide a flexible system which handles different types of user specified detour information in different desired manners. The end result is that in prior route planning systems the user may have to engage in time consuming additional effort in reentering or erasing prior detour data to ensure the use of prior detour data for subsequent trips in the manner which he desires.